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CVE-2025-15661

33
FAUCET Score

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

First published: Jun 18, 2026Last modified: Jul 14, 2026

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.11.1CPE matchmatch criteria
cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*
>= 0, <= 1.11.1CPE match
cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

8.3HIGH

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
LOW
VS Integrity
NONE
VS Availability
HIGH
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
1.03%
Probability of exploitation in next 30 days
EPSS Percentile
60.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0103 is in the 20th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (8)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: azl3 libssh2 1.11.1-3 on Azure Linux 3.0Fixed in: 1.11.1-4
microsoftpatch availablevia msrc
Product: azl3 libssh2 1.11.1-4 on Azure Linux 3.0Fixed in: 1.11.1-4
microsoftpatch availablevia msrc
Product: 21485-17084Fixed in: 1.11.1-4
microsoftpatch availablevia msrc
Product: 21559-17084Fixed in: 1.11.1-4
ubuntupatch availablevia ubuntu_usn
Product: libssh2 (resolute)Fixed in: 1.11.1-1ubuntu0.26.04.2
ubuntupatch availablevia ubuntu_usn
Product: libssh2 (noble)Fixed in: 1.11.0-4.1ubuntu0.24.04.2
ubuntupatch availablevia ubuntu_usn
Product: libssh2 (questing)Fixed in: 1.11.1-1ubuntu0.25.10.2

Vendor Advisories (2)

ubuntuUSN-8486-1

libssh2 vulnerabilities

Jun 30, 2026
microsoft2026-Jun/CVE-2025-15661Moderate

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

Jun 9, 2026

References

github.com / libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d
Patch
github.com / libssh2/libssh2/pull/1705
Patch
github.com / libssh2/libssh2/pull/1717
Patch
vulncheck.com / advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c
Third Party Advisory